1. Field of the Invention
The instant invention relates to a novel class of stable dispersions of a polymer in a polyol hereinafter called polymer/polyols) which can react with organic polyisocyanates to form polyurethane products. The invention also relates to novel polyurethane products prepared from such polymer/polyol. More specifically, this invention relates to a class of polymer/polyols prepared from substituted styrenes. It has surprisingly been found that substituted styrenes provide stable dispersions in a polyol, even when no greater than 20% acryonitrile is present as a comonomer, without adversely affecting the physical properties of the polymer/polyol or resulting polyurethane.
2. The Prior Art
The basic technology for the preparation of polymer/polyol dispersions useful in producing polyurethane foams, elastomers and the like is described in U.S. Pat. Nos. 3,304,273, 3,383,351, Re. 28,715 and Re. 29,118 to Stamberger. Such dispersions can be produced by polymerizing one or more olefinically unsaturated monomers dissolved or dispersed in a polyol in the presence of a free radical catalyst. Polymer/polyol dispersions, when used in producing polyurethane foams and elastomers, impart higher load bearing properties to polyurethane foams and elastomers than are exhibited by such products prepared from unmodified polyols.
Recently, polymer/polyols having higher styrene contents have become commercially attractive. Unfortunately, it is impossible to obtain high styrene contents without there occurring a corresponding loss in physical properties. The physical properties significantly affected by the styrene content are viscosity, dispersed polymer particle morphology, and potential solids level. Nonetheless, the art is replete with reference to styrenes as a monomer or comonomer useful in making polymer/polyols.
To list but a few of these references are Example 47 of U.S. Pat. No. 4,148,840; Example 53 of U.S. Pat. No. 4,242,249; Example 11 of U.S. Pat. No. 4,233,425; Example 60 of U.S. Pat. No. 4,454,255 and Example 44 of U.S. Pat. No. 4,458,038.
However, the art has failed to appreciate the unexpectedly superior abilities of the substituted styrenes monomer. Although a passing reference to these materials is generally found in most polymer/polyol patents, they have largely been ignored. Indeed, the only known examples to a substituted styrene are found in U.S. Pat. No. 4,458,038 as comonomers with acrylonitrile.
The unexpectedly superior performance of these substituted styrenic materials in polymer dispersions and their conversion into polyurethanes represent an advance over the existing technology and the potential for improved products.